Robot with floating XY plane arm

ABSTRACT

The present invention provides an apparatus and method of utilization thereof of a robot with a floating arm. The floating arm aspect of the robot allows the robot to align its associated tooling with the workpiece in situations where the workpiece may be in a variety at different locations. By use of the present invention the requirement for use of a vision system to accomplish alignment between the robot and the workpiece is eliminated.

FIELD OF THE PRESENT INVENTION

The field of the present invention is of robots and methods of utilizingthe same for performing operations on workpieces. More particularly thepresent invention relates to robots and methods of utilization of thesame for material handling operations.

DISCLOSURE STATEMENT

Robots are utilized in various operations in industry. One of the majoroperations of robots in industry is in the material handling area.Robots are often used to take a given workpiece from one storage area toa conveyer line or machining area.

When utilized in the machine handling mode, it is often common topresent the workpieces to the robot in a stacked position. The robotmust pick up the workpiece from the stacked position and then transportthe workpiece to a given storage area, conveyer line, or machining area.The workpieces can often be slightly warped or presented to the robot ina slightly mispositioned manner. The above-described conditions areoften present when using a robot to move plastic preform material trays.

Since the travel pattern of the robot is fixed, the position of theworkpiece or tray must be carefully maintained. Misalignment between therobotically held tool and the workpiece will cause a failure inoperation or possible damage to the tool or workpiece.

One method of overcoming the mispositioning of the presented workpieceis to incorporate into the robot an artificial vision system which looksfor the workpiece. Vision systems add complexity to the robot andincrease the possibilities of technical failures of the robot stoppingproduction. Vision systems often require markings or other preparationson the workpiece so that the robot may properly identify the workpieceor the workpiece's location. Also vision systems can significantlyincrease the cost associated with a robotic system.

Another method to provide compliance without the use of vision systemsis to provide a robotic arm with a deformable material such as rubber,captured between two metallic plates. The rubber will deform to providecompliance. The deformable type compliance devices are severely limitedin that they do not provide the amount of compliance needed in manyapplications. Also, deformable material compliance type devices areseverely limited in load capabilities as well as being subject tofatigue failure problems.

SUMMARY OF THE INVENTION

To overcome the above noted and other problems the present invention isbrought forth. The present invention provides a robot and method ofutilization of the same which has a floating arm. The use of thefloating arm allows the tool carried by the robot to align itself with agiven workpiece. In the preferred embodiment the arm of the robot hasprojecting pins which make contact with cam surfaces provided by theattached tool to fix the location of the tool with the arm. Thereforewhen the robot places the workpiece in a new desired area, the workpiecewill be in a proper orientation with respect to the robot regardless ofits original misaligned position. Also a vision system will not berequired to allow the robot to pick up a misaligned workpiece. The robotwill automatically compensate for misalignment between the programrobotic movement and the presented workpiece.

It is an object of the present invention to provide a robot with afloating arm. It is also an object of the present invention to provide arobot which allows the attached tooling to adjust to the position of theworkpiece without the use of an artificial vision system. It is also anobject of the present invention to provide a method of utilizing a robotto operate on a piece which may be misaligned in relation to the programtravel of the robotic arm.

More particularly an object of the present invention is to provide arobot with an extended arm for positioning an attached tool to perform agiven operation on a workpiece, said combination including base means tosupport said arm, transverse motion means to move said arm in a firsthorizontal plane, vertical motion means to move said arm perpendicularto said first horizontal plane, float means including a first bearingblock slidably mounted on a first shaft biased to a neutral poition anda second shaft transverse with said first shaft and attached with saidfirst bearing block, and a second bearing block connected with said tooland slidably mounted on said second shaft, said second bearing blockbeing biased to a neutral position allowing said arm to float in ahorizontal plane, whereby to facilitate the alignment of said tool witha workpiece, and tapered projectable pins connected with said arm havinga tapered surface for contact with guide means associated with said toolto fix the location of said tool in relation to said arm.

Other objects, desires and advantages of the present invention willbecome more apparent to those skilled in the art as the nature of theinvention is better understood from the accompanying drawings in adetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a robot of the present invention;

FIG. 2 is a top elevational view of an embodiment of the presentinvention.

FIG. 3 is a front elevational view partially in section of theembodiment illustrated in FIG. 2.

FIG. 4 is a side elevational view partially in section of the embodimentillustrated in FIG. 2.

FIG. 5 is a partial sectional view taken along lines 5--5 of FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1 robot 10 has a base 12 with a multi-membered armrepresented in total by item 14. The base provides a means of angularrotation to translate the robotic arm in a given plane usuallyorientated horizontally. The robotic arm bends along its joints 15 toallow the far end of the robotic arm to be translated in a line at apredetermined angle with its horizontal translation. The robot 10 canperform its horizontal and vertical translations separately orsimultaneously. At the end of the robotic arm 14 is a robotic wrist 16,a wrist extension 21, and a lower arm 17 which has attached thereto anoperational tool 18. As will be explained in more detail at a later timeoperational tool 18 is provided to grip the workpiece 50 which is to betransported by the robot 10.

Referring to FIGS. 2, 3 and 4, the robotic lower arm 17 is providedhaving a mounting plate 20 which provides a surface of attachment towrist extension 21. The mounting plate 20 has at its opposite endsfixably connected thereto tapered locking pins 22 whose function will bedescribed at a later point.

Tool 18 is provided with compliance (float) in the X and Y directions inrelationship to the top plate 20 by lower arm 17. Fixably connected withand extending downward from plate 20 are four X shaft support members 26which support two parallel X shafts 27. Plate 20, X shaft support 26 andX shafts 27 are fixed to one another.

Slidably mounted on the X shafts 27 are four X bearing blocks 28. The Xbearing blocks 28 are fixably connected with one another and also havedescending from them integrally joined Y shaft support members 38.Fixably joined to Y shaft support members 38 are two parallel Y shafts34 which are transversely mounted in relationship to the X shafts 27.

Tool 18 is fixably connected to four Y bearing blocks 36 via plate 60(FIG. 5) which are in turn slidably mounted on the two Y shafts 34.

The X bearing blocks 28 are provided with clearances 30 between thebearing blocks 28 and the X shaft support 26. To maintain the X bearingblocks 28 in a preset or neutral position there is provided biasingsprings 32. In like manner the Y bearing blocks 36 have a clearance 39.Biasing springs 37 position the Y shafts 34 to a neutral position.

Referring to FIGS. 1, 2, 3, 4 and 5, in operation the robotic arm 14 istransversely displaced in a first plane by the robotic base 12.Separately or simultaneously the robotic arm 14 will move in a verticaldirection having a fixed angular orientation with the first plane. Thetapered tool pick up levers 42 will make the first initial contact withthe box shown as 50. The cam surface 45 on the pick up levers causes thetool 18 to be urged into an orientation to properly pick up the box 50.The combination of the tool 18 and the robotic lower arm 17 will act asthree separate members. Since the tool 18 is rigidly connected with thebearing block 36, Y compliance will be provided by translational slidingmotion of the Y bearing blocks 36 upon Y shaft 34. Compliance in the Xdirection will be provided by translational sliding motion between Xbearing blocks 28 and X shafts 27.

When the tool 18 is placed in the proper position in relationship to thebox 50, the pick up levers 42 will be activated by cylinder 70.

After the robotic levers 42 are activated to pick up the box 50, thealignment pins 22 connected with air cylinders 23 are projecteddownwards. A tapered surface 64 of the alignment pins will then makecontact with a guide cam tapered surface 66 provided upon tool 18,bringing the tool 18 into a fixed position with respect to the roboticlower arm 17. Therefore upon the robot 10 transporting the workpiece 50to a new location, the workpiece 50 will be at an exact aligned positionwith respect to robotic lower arm 17 as desired regardless of itsinitial position when picking up the workpiece.

One advantage provided by the present invention is that by the simplelengthening of the X or Y shafts the maximum compliance allowable forthe robotic arm may be easily modified.

The method of the present invention for utilizing a robot having an armextended from a robotic base support to positioning the robotic arm in adesired location in relationship to a workpiece includes the followingsteps of:

1. Supporting a robotic arm from a robotic place.

2. Displacing the robotic arm in a first plane.

3. Displacing said robotic arm along a fixed line at a predeterminedangle with the first plane.

4. Floating the tool only in a second fixed plane at a predeterminedangle with the fixed line to align the tool with the workpiece byrelative sliding motion in a plane between two members of the arm.

While a few of the embodiments of the present invention have beenexplained it will be readily apparent to those skilled in the art of thevarious modifications which can be made to the present invention withoutdeparting from the spirit and scope of this application as it isencompassed by the following claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follow:
 1. A robot with an extendedarm for positioning an attached tool to perform a given operation on aworkpiece, said robot in combination comprising:base means to supportsaid arm; transverse motion means to move said arm in a first horizontalplane; vertical motion means to move said arm perpendicular to saidfirst horizontal plane; float means for supporting an attached toolincluding a first bearing block slidably mounted on a first shaft, and asecond shaft transverse with said first shaft and attached with saidfirst bearing block, and a second bearing block slidably mounted on saidsecond shaft and connected with said tool allowing said tool to floatonly in a plane fixed with respect to said first horizontal plane,whereby to facilitate the alignment of said tool with a workpiece; andtapered pins connected with said arm having a tapered surface forcontact with guide means associated with said tool to fix the locationof said tool in relation to said arm.
 2. A robot as described in claim 1wherein said tapered pins are vertically retractable.
 3. A robot asdescribed in claim 1 further including biasing means biasing said firstand second bearing blocks to a preset position.
 4. A method of utilizinga robot with an arm with an attached tool which is extended from arobotic base support to position the robot in a desired location inrelationship to a workpiece to perform an operation on said workpiece,said method including in combination:supporting a robot arm from a robotbase; displacing said robot arm in a first plane; displacing said robotarm along a fixed line at a predetermined angle with said manner firstplane; floating said tool only in a fixed second plane at apredetermined angle with said fixed line to align said tool with saidworkpiece by translational sliding motion of two members which supportthe tool relative to each other and the arm; and locking the location ofsaid tool by locking said two members in relation to said arm subsequentto floating said tool to align said tool with said workpiece.
 5. Amethod as described in claim 4 further projecting tapered pins connectedwith said arm into guide cam surfaces of said tool.